A new study from Leiden University in the Netherlands has found that the increasing levels of carbon dioxide in the climate are making food higher in calories but lower in nutrients, and it may even increase toxicity.
According to a report by The Guardian on Friday, led by lecturer Sterre ter Haar from Leiden University, the research on plant responses to increased carbon dioxide levels compiled nearly 60,000 measurement data from 109 studies, covering 43 crops including rice, potatoes, tomatoes, and wheat, and 32 nutrients.
The study set the baseline measurement value for carbon dioxide at 350 ppm (ppm stands for parts per million, indicating how many carbon dioxide molecules are present per million air molecules in volume) — sometimes referred to as the last “safe” level. They compared this to 550 ppm, a level some scientists project to be reached around 2065. They stated that most nutrients have negative reactions after the rise in carbon dioxide levels, with an average decrease of 3.2%.
Research results show that with the increase of carbon dioxide, plants uptake more carbon, leading to an increase in carbohydrates such as sugar and starch in food, making the calorie content relatively higher. However, at the same time, key nutrients like iron, zinc, and protein decrease, with an average reduction of about 3.2%. In some foods, the decrease in key nutrients is more significant, for example, zinc in chickpeas is expected to decrease by up to 37.5%, and protein, zinc, and iron content in major crops like rice and wheat are also significantly reduced.
Ter Haar stated that the resulting effect is that while crop yields may increase, the nutrient density decreases. This is not merely a dilution effect but a complete transformation of food composition.
She told the media that the drastic extent of some nutrient changes, as well as differences between different plants, are surprising and raise questions about the need to adjust dietary structures or change food production methods.
The study also noted that heavy metals like lead in food may increase as a result, raising serious concerns as even low levels of lead can cause poisoning, potentially damaging the brain, heart, and nervous system. However, the study did not specifically track heavy metals and could not draw a definitive final conclusion, requiring further examination.
Researchers warned that this change could lead to “hidden hunger,” where there is an abundance of calories but insufficient nutrients, with devastating health consequences. Additionally, if food calories increase while nutrients decrease, there could be a scenario of both average weight gain and malnutrition.
The current atmospheric carbon dioxide concentration is around 425 ppm-426 ppm, already midway through the process of potentially impactful simulation.
Courtney Leisner, an assistant professor at Virginia Tech’s College of Plant and Environmental Sciences, welcomed the study, stating that it provides crucial data on how environmental conditions affect crop nutrient quality, which is essential for maintaining future food security.
Jan Verhagen, a researcher in climate change and sustainable agriculture at Wageningen University in the Netherlands, pointed out that nutrient levels in plants are indeed changing, but whether this is solely related to carbon dioxide remains debatable.
He emphasized that other factors such as fertilizer application also play vital roles, necessitating more experiments and breeding programs to better understand the climate’s impact on agriculture.
The Netherlands is one of the world’s major agricultural exporting countries, with over 4,100 hectares of greenhouse cultivation widely using methods of growing crops in carbon dioxide-rich environments to increase yields.
Ter Haar emphasized that climate change is not a distant issue, as its impact is already showing up on our plates. We may need to reconsider the future of healthy eating, with a diverse diet being able to buffer potential impacts.
The study calls for recognizing the issue and further research to address the direct impact of rising carbon dioxide on crop nutrients.